Here’s why it’s difficult to predict whether your relationship will last

When you meet someone new and sparks fly, you might be tempted to wonder if the relationship is for the keeps or is it just a short-term affair. But it takes a while for the differences in short-term and long-term relationships to emerge.

If there’s one thing difficult to predict, it’s human emotions and how people might behave in romantic relationships. Typically, when people get into new relationships, they spend days pondering if the person is ‘the one’ for them or just good for a casual fling. They look for signs which give a hint.

Researchers say that romantic interest rises at the same rate in both short-term and long-term relationships. (Shutterstock)

However, it is not so easy to tell.

According to a study led by the University of California, in the beginning, long-term and short-term relationships may look more or less identical. When you survey the complete time course of a short-term and long-term relationship - from the moment you meet someone until the moment the relationship is over for good - it takes a while for the differences in short-term and long-term relationships to emerge.

“Long-term and short-term trajectories typically pull apart after you’ve known someone for weeks or months,” said Paul Eastwick, the lead author on the study.“In the beginning, there is no strong evidence that people can tell whether a given relationship will be long-term and serious or short-term and casual.”

Eastwick and his co-authors surveyed more than 800 people from a wide range of ages. They used a state-of-the-art ‘relationship reconstruction’ survey in which people reproduce the events and experiences they had in their prior real-life short-term and long-term relationships.

According to research, Some of the most interesting moments in these relationships happen after you meet the person face-to-face, but before anything sexual has happened. (Shutterstock)

Importantly, the researchers asked the participants to reconstruct these relationships from the very beginning. This procedure differs from the standard ‘relationship science’ approach, which starts studying people once they are already in a dating relationship. “Some of the most interesting moments in these relationships happen after you meet the person face-to-face, but before anything sexual has happened,” Eastwick added. “You wonder ‘is this going somewhere?’ or ‘How much am I into this person?’ It is somewhere around this point that short-term and long-term relationships start to diverge, and historically, we have very little data on this particular period of time.”

The researchers found that romantic interest rises at the same rate in both short-term and long-term relationships. But at some point, romantic interest tends to plateau and decline in short-term relationships, while in long-term relationships, it continues to ascend and reaches a higher peak.

What is the moment when the two trajectories start to diverge? On average, it happens at about the time that the relationship starts to become sexual. “People would hook up with some partners for the first time and think ‘wow, this is pretty good.’ People tried to turn those experiences into long-term relationships,” said Eastwick. “Others sparked more of a ‘meh’ reaction. Those were the short-term ones.”

The study offered a new twist on the distinction between the stable, long-term partner and the exciting, short-term partner. In real life, people may end up in short-term relationships when they are ‘just a little’ attracted to the other person - enough to keep having sex, but maybe not for very long. Long-term relationships may be the ones that start especially exciting and sexy and grow into something stable and lasting.

The study appears in the Journal of Experimental Psychology: General.

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